The Input menu appears in the upper-right corner of the menu bar at the top of your computer screen. Its icon is usually the flag of the country that corresponds to the input source you have chosen in Language & Text preferences. For example, if you chose U.S., the American flag is the icon for the Input menu. When you switch to a Dvorak keyboard, the icon changes accordingly.

You can view the selected Dvorak layout on your computer screen by using Keyboard Viewer.

In Keyboard preferences, select the “Show Keyboard & Character Viewer in menu bar” checkbox. Then in the Input menu in the upper-right corner of the menu bar at the top of your computer screen, choose Show Keyboard Viewer.